1. Field of the Invention
The present invention relates to a driving apparatus and method of an induction motor and, more particularly, to a driving apparatus and method of an induction motor that are capable of preventing a power-factor degradation possibly caused in supplying a DC voltage to an inverter to drive a three phase induction motor, removing a harmonic wave, and capable of reducing an expense by not using a high-priced inverter component.
2. Description of the Background Art
In general, an induction motor is used to drive an air-conditioner. The induction motor signifies a motor consisting of a stator which is not rotated and a rotor which is rotatable.
In other words, when a current is supplied to generate a rotating magnetic field at a coil wound on, an induction current flows at the rotor winding due to an electromagnetic induction, according to which torque is generated to rotate the induction motor.
FIG. 1 shows a construction of a driving apparatus of a single-phase induction motor in accordance with a conventional art.
As shown in FIG. 1, when a single phase 220V AC voltage is supplied from a single-phase power supply unit 1, a rectifier 2 rectifies it to a DC voltage of about 300V. The rectified voltage is boosted to about 400V through a power circuit unit 3 and transferred to an inverter unit. Then, the induction motor is finally driven.
Recently, in order to drive the air-conditioner, a three-phase induction motor using three-phase power is increasingly used.
FIG. 2 is a block diagram showing a construction of a driving apparatus of the three-phase induction motor in accordance with the conventional art.
As shown in FIG. 2, the apparatus for driving the three-phase induction motor includes: a three-phase power supply unit 11 for supplying three-phase 380V voltage; a rectifier 12 for rectifying the three-phase voltage; and an inverter unit 13 for driving a three-phase induction motor 14 according to the voltage which has been rectified to a DC voltage of 530V by the rectifier unit 12.
However, because the three-phase induction motor driving apparatus rectifies the high voltage and repeatedly supplies it to the inverter unit, a power-factor is inevitably degraded and a harmonic wave is inevitably generated.
In addition, in order to implement the inverter unit, a high-priced inverter circuit component with a withstand voltage of 1200V should be used. In such a case, an expense required for implementing the driving apparatus of the three-phase induction motor is increased and a high voltage-purposed compressor, not a low voltage-purposed compressor used for the existing single-phase power supply system, should be newly developed for use.